The same day it was warning the public about bogus H1N1 vaccines being sold over the Internet, the U.S. Food and Drug Administration issued a warning letter ordering one such Web-based company to halt its sale of an unapproved Swine Flu product.

The FDA, in conjunction with the Federal Trade Commission, issued a joint warning letter to Weil Lifestyle, LLC, a company marketing what the two agencies claim are fraudulent supplements that claim to help prevent the spread of the H1N1 influenza virus.

The warning letter, the first to be issued jointly by the agencies, orders owners of the site to discontinue marketing their product or face legal action. The letter also gave the owners of the site, www.drweil.com, 48 hours to provide the federal agencies a plan to discontinue the fraudulent marketing.

The product in question was advertised as “Immune Support Formula.” Some sales of the product were believed to have been made in the Houston area.

“The marketing of this product violates the Federal Food, Drug and Cosmetic Act,” the warning letter said. “We request that you immediately cease marketing unapproved, uncleared or unauthorized products for the diagnosis, mitigation, prevention, treatment or cure of the H1N1 flu virus.”

The warning also pointed out that FTC regulations require “that claims of a dietary supplement can prevent, treat or cure human infection with the H1N1 virus must be supported by well-controlled human clinical studies at the time the claims are made.”

“More generally, it is against the law to make or exaggerate health claims, whether directly or indirectly, through the use of a product name, website name, metatags or other means without rigorous scientific evidence sufficient to substantiate the claims,” the letter went on to say. “Violations of the FTC Act may result in legal action in the form of a Federal District Court injunction or administrative order. An order also may require that you pay back money to consumers.”

The FDA and FTC also reminded consumers to be cautious of promotions or Internet sites offering products for sale that claim to diagnose, prevent, mitigate, treat or cure the 2009 H1N1 influenza virus. Fraudulent H1N1 influenza products come in many varieties, the agencies pointed out, including dietary supplements, as well as products purporting to be drugs, medical devices or vaccines.

Since May 2009, the FDA has warned more than 75 websites to stop the sale of more than 135 products with fraudulent H1N1 influenza virus claims.

“Products that are offered for sale with claims to diagnose, prevent, mitigate, treat or cure the 2009 H1N1 influenza virus must be carefully evaluated,” said Commissioner of Food and Drugs Margaret A. Hamburg, M.D. “Unless these products are proven to be safe and effective for the claims that are made, it is not known whether they will prevent the transmission of the virus or offer effective remedies against infection. Furthermore, they can make matters worse by providing consumers with a false sense of protection.”

The two federal agencies also warned consumers to take extreme care when buying such products over the Internet because, in addition to being fraudulent, they could also be dangerous.

FDA Acting Associate Commissioner for Regulatory Affairs Michael Chappell said his agency and the FTC will continue to work aggressively to identify, investigate and take action against individuals or businesses that fraudulently promote purported 2009 H1N1 influenza products.

“The FDA continues to consider the sale and promotion of fraudulent H1N1 influenza products to be a possible threat to the public health and in violation of the Federal Food Drug and Cosmetic Act,” Chappell said. “The FDA has an aggressive surveillance program to detect fraudulent H1N1-related products and will take prompt action to stop the marketing of fraudulent H1N1 influenza products and will hold those who are responsible for doing so accountable.”